Methods, apparatuses, related computer program product and data structure for deciding on a signaling scheme for handover

ABSTRACT

A first method (and related first apparatus) includes transmitting, in a handover request message, an indication of a first protocol version; a second method (and related second apparatus) includes receiving, in the handover request message, the indication, deciding, based on the received indication and a second protocol version, on a value of an information element included in a handover request acknowledgement message to be transmitted, the information element indicating usage of a first or second signaling scheme, and transmitting the handover request acknowledgement message including the information element; and in the first method receiving the handover request acknowledgement message including the information element; and a third method (and related third apparatus) including receiving the handover command message including the information element, and configuring according to one of the first and second signaling schemes indicated by the information element.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/753,448, filed on Jun. 29, 2015, which is a continuation of U.S.patent application Ser. No. 14/609,101, filed on Jan. 29, 2015, whichissued as U.S. Pat. No. 9,072,012 on Jun. 30, 2015, which is acontinuation of U.S. patent application Ser. No. 14/593,759, filed onJan. 9, 2015, which issued as U.S. Pat. No. 9,055,489 on Jun. 9, 2015,which is a continuation of U.S. patent application Ser. No. 14/178,418,filed on Feb. 12, 2014, which issued as U.S. Pat. No. 9,049,623 on Jun.2, 2015, which is a continuation of U.S. patent application Ser. No.13/516,399, filed on Jul. 24, 2012, which issued as U.S. Pat. No.8,665,830 on Mar. 4, 2014, which is a National Stage Application of andclaims the benefit of PCT/EP2009/067218, filed on Dec. 15, 2009, thecontents of which are hereby incorporated by reference herein.

FIELD OF INVENTION

An example of the present invention relates to deciding on a signalingscheme for handover. More specifically, the example of the presentinvention relates to methods, apparatuses, a related computer programproduct and a data structure for deciding on a signaling scheme forhandover. The example of the present invention may be applicable e.g. tointra-long term evolution (LTE) and inter-evolved node B (eNB) handoverin the 3rd generation partnership project (3GPP).

BACKGROUND

In LTE Release 8 (Rel-8), e.g. for reducing the size or configuration ofhandover command message (e.g. radio resource controller (RRC)connection reconfiguration message), 3GPP decided to use the so-calleddelta signaling. This means that in case a target eNB does not includee.g. a parameter in the handover command, a user equipment (UE) mayassume that the parameter or function will continue after the handover.

However, in the current universal mobile telecommunication system (UMTS)(e.g. so-called 3G system), e.g. the so-called inter-radio networkcontroller (RNC) handover does not use this kind of scheme, but in caseof a UE involving e.g. radio network system (RNS) relocation (e.g. hardhandover), a target RNC may constructs a handover command message basedon the radio access bearer (RAB) information. This means that the targetRNC may explicitly include parameters to be used after the handover.

There have been approaches dedicated to solve the above issues.

For example, a full signaling configuration may be used. However, in3GPP, there are no considerations on how the target eNB may choose usageof either a so-called delta signaling or full signaling.

However, the delta signaling assumes that the source eNB and the targeteNB are using the same RRC protocol release or target eNB RRC protocolrelease is newer than the one of the source eNB. However, e.g. in casethat the target eNB RRC protocol release is earlier than that of thesource eNB, an additional rule may be required because by no means canthe target eNB continue a later release functionality after thehandover. Thus, all additional functionality and parameters defined inlater release may be released.

In consideration of the above, according to the example of the presentinvention, methods, apparatuses, a related computer program product anda data structure for deciding on a signaling scheme for handover areprovided.

In this connection, the examples of the present invention enable one ormore of the following:

-   -   Specifying a logic for the target eNB to choose usage of either        delta signaling or full signaling;    -   Enabling a parameter exchange to assist the target eNB in making        the above decision;    -   Avoiding a complicated network, and thus, avoiding a complicated        operation and management (O&M) configuration effort;    -   Providing a simple logic for the target eNB dealing on when to        use delta signaling and when to use full configuration        signaling.

BRIEF DESCRIPTION OF THE DRAWINGS

The examples of the present invention are described herein below withreference to the accompanying drawings, in which:

FIG. 1 shows methods for deciding on a signaling scheme for handoveraccording to an example of the present invention;

FIG. 2 shows apparatuses for deciding on a signaling scheme for handoveraccording to the example of the present invention; and

FIG. 3 shows a data structure for deciding on a signaling scheme forhandover according to the example of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The example of the present invention is described herein below by way ofexample with reference to the accompanying drawings.

It is to be noted that for this description, the terms “protocolrelease; at least one bit; radio resource control connectionreconfiguration message; radio resource control protocol; fullsignaling; and delta signaling” are examples for “protocol version;information element; the message to be sent to UE to command thehandover; first and second protocols; signaling scheme using handovercommand messages of full configuration (e.g. parameters); and signalingscheme using handover command messages of reduced configuration”,respectively, without restricting the latter-named terms to the specialtechnical or implementation details imposed to the first-named terms.

FIG. 1 shows the methods for deciding on a signaling scheme for handoveraccording to the example of the present invention. Signaling betweenelements may be indicated in horizontal direction, while time aspectsbetween signaling may be reflected in the vertical arrangement of thesignaling sequence as well as in the sequence numbers. It is to be notedthat the time aspects indicated in FIG. 1 do not necessarily restrictany one of the method steps shown to the step sequence outlined. Thisapplies in particular to method steps that are functionally disjunctivewith each other. Within FIG. 1, for ease of description, means orportions which may provide main functionalities are depicted with solidfunctional blocks or arrows and/or a normal font, while means orportions which may provide optional functions are depicted with dashedfunctional blocks or arrows and/or an italic font.

As shown in FIG. 1, a communication system 200 may comprise a UE 201 anda network 202. In turn, the network 202 may further comprise a sourceeNB 2021 and a target eNB 2022, the terms “target” and “source” relatinge.g. to a handover relationship between the eNBs 2021, 2022.

At the beginning, in an optional preparatory step S0, e.g. the UE 201and the source eNB 2021 may perform conducting a measurement procedureand a decision of the source eNB 2021 to perform a handover (HO).

Further, as shown in FIG. 1, in step S1-1, e.g. the source eNB 2021 mayperform transmitting, in a handover request message, an indication (e.g.enumerated information element) of a first protocol version (e.g. RRCprotocol version of the source eNB 2021). Then, in step S2-1, e.g. thetarget eNB 2022 may perform receiving, in the handover request message,the indication of a first protocol version.

In step S2-2, e.g. the target eNB 2022 may perform deciding, based onthe received indication (e.g. RRC indication) of the first protocolversion and a second protocol version (e.g. RRC protocol version of thetarget eNB 2022), on a value of an information element (e.g. one bit)comprised in a handover request acknowledgement message (e.g. RRCconnection reconfiguration message which may be encapsulated in ahandover request acknowledgement message) to be transmitted, theinformation element indicating usage of one of a first signaling scheme(e.g. delta signaling) and a second signaling scheme (e.g. fullsignaling) different from the first signaling scheme.

And, in step S2-3, e.g. the target eNB 2022 may perform transmitting thehandover request acknowledgement message (which may contain RRCConnection Reconfiguration message) comprising the information elementindicating usage of the one of the first and second signaling (e.g.delta signaling or full signaling) schemes. Accordingly, in step S1-2,e.g. the source eNB 2021 may perform receiving, responsive to thetransmitting in step S1-1, the handover request acknowledgement message(e.g. containing RRC Connection Reconfiguration message) comprising theinformation element indicating usage of one of the first signalingscheme and the second signaling scheme, the usage of the one of thefirst and second signaling schemes having been decided based on thefirst protocol version and the external second protocol version.

In an optional step S1-3, e.g. the source eNB 2021 may performextracting a handover command message from the received handover requestacknowledgement message, the handover command message comprising theinformation element.

Then, in step S1-4, e.g. the source eNB 2021 may perform transmitting,after the receiving, the handover command message (e.g. RRC ConnectionReconfiguration message) to a user equipment (e.g. UE 201).

Finally, in step S3-2, e.g. the UE 201 may perform receiving thehandover command message comprising the information element. And, instep S3-2, e.g. the UE 201 may perform configuring according to thefirst or the second signaling scheme indicated by the informationelement.

As for developments pertaining to the target eNB 2022, the deciding maybe performed during a handover preparation. Further, the indication ofthe first protocol version (e.g. RRC protocol version of the source eNB2021) may be comprised in a radio resource control container, or may besignaled in an X2/S1 application signaling protocol.

As for developments pertaining to both the source eNB 2021 and thetarget eNB 2022, the first signaling scheme may utilize a radio resourcecontrol container defined in radio resource control specification (e.g.handover preparation information messages). In that case, theinformation element may be set to affirmative. Further in this case, thefirst protocol version (e.g. RRC protocol version of the source eNB2021) may be higher than the second protocol version (e.g. RRC protocolversion of the target eNB 2022). Alternatively, the second signalingscheme may utilize a message defined in X2 application protocolspecification (e.g. handover request message) or S1 application protocolspecification. (e.g. handover required message) In that case, theinformation element may be set to non-affirmative. Further in this case,the first protocol version may be equal to or lower than the secondprotocol version. However, the same information should be transferredfrom the source eNB 2021 to the target eNB 2022 regardless the signalingscheme. Further, the protocol version may be constituted by a protocolrelease. In addition, the information element may be constituted by atleast one bit. Still further, the handover request acknowledgementmessage may be constituted by or may encapsulate a radio resourcecontrol connection reconfiguration message. Moreover, the first protocolmay be constituted by a radio resource control protocol of a handoversource entity, while the indication of the first protocol version may bean enumerated information element. Further, the second protocol mayconstituted by a radio resource control protocol of a handover targetentity. Finally, the handover command messages of full configuration orof delta configuration may be constituted by radio resource controlconnection reconfiguration messages, while the radio resource controlcontainer may be constituted by a handover preparation informationmessage.

FIG. 2 shows apparatuses (e.g. the UE 201, the source eNB 2021 and thetarget eNB 2022) for deciding on a signaling scheme for handoveraccording to the example of the present invention. Within FIG. 2, forease of description, means or portions which may provide mainfunctionalities are depicted with solid functional blocks or arrowsand/or a normal font, while means or portions which may provide optionalfunctions are depicted with dashed functional blocks or arrows and/or anitalic font.

The UE 201 may comprise a CPU (or circuitry) 2011, a memory 2012, anoptional transmitter (or means for transmitting) 2013, a receiver (ormeans for receiving) 2014 and a configurator (or means for configuring)2015.

The source eNB 2021 may comprise a CPU (or circuitry) 20211, a memory20212, a transmitter (or means for transmitting) 20213, a receiver (ormeans for receiving) 20214 and an optional extractor (or means forextracting) 20215.

The target eNB 2022 may comprise a CPU (or circuitry) 20221, a memory20222, a transmitter (or means for transmitting) 20223, a receiver (ormeans for receiving) 20224 and a decider (or means for deciding) 20225.

As indicated by the dashed extensions of the functional blocks of theCPU 2011, 20211 or 20221, the means for configuring 2015, the means forextracting 20215 and the means for deciding 20225 (and the means fortransmitting 2013 and means for receiving 2014 of the UE 201, the meansfor transmitting 20213 and means for receiving 20214 of the source eNB2021 as well as the means for transmitting 20223 and means for receiving20224 of the target eNB 2022) may be functionalities running on the CPU2011, 20211 or 20221 of the UE 201 and/or source and target eNBs 2021,2022, or may alternatively be separate functional entities or means.

The CPUs 20 x 1 (wherein x=1, 21 and/or 22) may respectively beconfigured, for example by software residing in the memory 20 x 2, toprocess various data inputs and to control the functions of the memories20 x 2, the means for transmitting 202 x 3 and the means for receiving20 x 4 (as well as the means for configuring 2015 of the UE 201, themeans for extracting 20215 and the means for deciding 20225 of thetarget eNB 2022). The memories 20 x 2 may serve e.g. for storing codemeans for carrying out e.g. the methods according to the example of thepresent invention, when run e.g. on the CPUs 20 x 1. It is to be notedthat the means for transmitting 20 x 3 and the means for receiving 20 x4 may alternatively be provided as respective integral transceivers. Itis further to be noted that the transmitters/receivers may beimplemented i) as physical transmitters/receivers for transceiving e.g.via the air interface (e.g. between the UE 201 and the source entity2021), ii) as routing entities e.g. for transmitting/receiving datapackets e.g. in a PS (packet switching) network (e.g. between the sourceeNB 2021 and the target eNB 2022 when disposed as separate networkentities), iii) as functionalities for writing/reading informationinto/from a given memory area (e.g. in case of shared/common CPUs ormemories e.g. of the source eNB 2021 and the target eNB 2022 whendisposed as an integral network entity), or iv) as any suitablecombination of i) to iii).

Further, as shown in FIG. 2, e.g. the means for transmitting 20213 ofthe source eNB 2021 may perform transmitting, in a handover requestmessage, an indication (e.g. enumerated information element) of a firstprotocol version (e.g. RRC protocol version of the source eNB 2021).Then, e.g. the means for receiving 20224 of the target eNB 2022 mayperform receiving, in the handover request message, the indication of afirst protocol version.

For example, the means for deciding 20225 of the target eNB 2022 mayperform deciding, based on the received indication (e.g. RRC indication)of the first protocol version and a second protocol version (e.g. RRCprotocol version of the target eNB 2022), on a value of an informationelement (e.g. one bit) comprised in a handover request acknowledgementmessage (e.g. RRC connection reconfiguration message which may beencapsulated in a handover request acknowledgement message) to betransmitted, the information element indicating usage of one of a firstsignaling scheme (e.g. delta signaling) and a second signaling scheme(e.g. full signaling) different from the first signaling scheme.

And, e.g. the means for transmitting 20223 of the target eNB 2022 mayperform transmitting the handover request acknowledgement message (whichmay contain RRC Connection Reconfiguration message) comprising theinformation element indicating usage of the one of the first and secondsignaling (e.g. delta signaling or full signaling) schemes. Accordingly,e.g. the means for receiving 20214 of the source eNB 2021 may performreceiving, responsive to the transmitting performed by the means fortransmitting 20213, the handover request acknowledgement message (e.g.containing RRC Connection Reconfiguration message) comprising theinformation element indicating usage of one of the first signalingscheme and the second signaling scheme, the usage of the one of thefirst and second signaling schemes having been decided based on thefirst protocol version and the external second protocol version.

Optionally, e.g. the means for extracting 20215 of the source eNB 2021may perform extracting a handover command message from the receivedhandover request acknowledgement message, the handover command messagecomprising the information element.

Then, optionally, e.g. the means for transmitting 20213 of the sourceeNB 2021 may perform transmitting, after the receiving, the handoverrequest acknowledgement message (e.g. RRC Connection Reconfigurationmessage) to a user equipment (e.g. UE 201).

Finally, e.g. the means for receiving 2014 of the UE 201 may performreceiving the handover command message comprising the informationelement. And, e.g. the means for configuring 2015 of the UE 201 mayperform configuring according to the first or the second signalingscheme indicated by the information element.

As for developments pertaining to the target eNB 2022, the means fordeciding 20225 may be configured to perform during a handoverpreparation. Further, the indication of the first protocol version (e.g.RRC protocol version of the source eNB 2021) may be comprised in a radioresource control container, or may be signaled in an X2/S1 applicationsignaling protocol.

As for developments pertaining to both the source eNB 2021 and thetarget eNB 2022, the first signaling scheme may utilize a radio resourcecontrol container defined in radio resource control specification (e.g.handover preparation information messages). In that case, theinformation element may be set to affirmative. Further in this case, thefirst protocol version (e.g. RRC protocol version of the source eNB2021) may be higher than the second protocol version (e.g. RRC protocolversion of the target eNB 2022). Alternatively, the second signalingscheme may utilize a message defined in X2 application protocolspecification (e.g. handover request message) or S1 application protocolspecification. (e.g. handover required message) In that case, theinformation element may be set to non-affirmative. Further in this case,the first protocol version may be equal to or lower than the secondprotocol version. However, the same information should be transferredfrom the source eNB 2021 to the target eNB 2022 regardless the signalingscheme. Further, the protocol version may be constituted by a protocolrelease. In addition, the information element may be constituted by atleast one bit. Still further, the handover request acknowledgementmessage may be constituted by or may encapsulate a radio resourcecontrol connection reconfiguration message. Moreover, the first protocolmay be constituted by a radio resource control protocol of a handoversource entity, while the indication of the first protocol version may bean enumerated information element. Further, the second protocol mayconstituted by a radio resource control protocol of a handover targetentity. Finally, the handover command messages of full configuration orof delta configuration may be constituted by radio resource controlconnection reconfiguration messages, while the radio resource controlcontainer may be constituted by a handover preparation informationmessage.

Furthermore, at least one of, or more of the above-described means fortransmitting 20213, 20223, means for receiving 20214, 20224, means forconfiguring 2015, means for extracting 20215 and means for deciding20225 as well as the UE 201, source eNB 2021 and the target eNB 2022, orthe respective functionalities carried out, may be implemented as achipset, module or subassembly.

Finally, the example of present invention also relates to a system whichmay comprise the source eNB 2021, the target eNB 2022 and, the UE 201according to the above-described example of the present invention.

FIG. 3 shows a data structure 300 for deciding on a signaling scheme forhandover according to the example of the present invention.

As shown in FIG. 3, the data structure 300 may comprise an informationelement 301 indicating usage of one of the first signaling scheme (e.g.delta signaling scheme) and the second signaling scheme (e.g. fullsignaling scheme), the usage of the one of the first and secondsignaling schemes having been decided based on the first protocolversion (e.g. RRC protocol version of the source eNB 2021 signaled e.g.during handover preparation to the target eNB 2021) and the externalsecond protocol version (e.g. the RRC protocol version which the targeteNB 2022 is configured to support).

Further, the data structure may comprise an optional header 302, anoptional payload section 303 and an optional trailer 304.

As for developments pertaining to the data structure, the data structuremay be constituted by a handover request acknowledgement message.Further, the first signaling scheme may utilize a radio resource controlcontainer defined in radio resource control specification (e.g. handoverpreparation information messages). In that case, the information elementmay be set to affirmative. Further in this case, the first protocolversion (e.g. RRC protocol version of the source eNB 2021) may be higherthan the second protocol version (e.g. RRC protocol version of thetarget eNB 2022). Alternatively, the second signaling scheme may utilizea message defined in X2 application protocol specification (e.g.handover request message) or S1 application protocol specification.(e.g. handover required message) In that case, the information elementmay be set to non-affirmative. Further in this case, the first protocolversion may be equal to or lower than the second protocol version.However, the same information should be transferred from the source eNB2021 to the target eNB 2022 regardless the signaling scheme. Further,the protocol version may be constituted by a protocol release. Inaddition, the information element may be constituted by at least onebit. Still further, the handover request acknowledgement message may beconstituted by or may encapsulate a radio resource control connectionreconfiguration message. Moreover, the first protocol may be constitutedby a radio resource control protocol of a handover source entity, whilethe indication of the first protocol version may be an enumeratedinformation element. Further, the second protocol may constituted by aradio resource control protocol of a handover target entity. Finally,the handover command messages of full configuration or of deltaconfiguration may be constituted by radio resource control connectionreconfiguration messages, while the radio resource control container maybe constituted by a handover preparation information message.

Without being restricted to the details following in this section, theexamples of the present invention may be summarized as follows:

For example, if a new channel quality indicator (CQI) reportingparameter is defined in Rel-9 and the UE is configured with the new CQIreporting parameter in the Rel-9 source eNB, this new CQI reportingparameter should be released upon handover to Rel-8 eNB. However, as theRel-8 eNB does not support this functionality, it will not have anymeans to release this functionality nor can it properly interact withthe UE that continues using that functionality.

Accordingly, considerations are made on how to cope with the handover(HO) when a source eNB and a target eNB are using e.g. differentprotocol versions or releases. Basically, the example of the inventionprovides a mechanism to indicate which RRC (radio resource control)protocol version (release) is used in the source eNB, and therefore anew parameter may be added e.g. to a Handover Preparation Informationmessage, and based on that, the target eNB may be able to make adecision whether the full or delta signaling is needed to successful HOcompletion and to indicate it to the UE. In other words, this means thatthis indicator may tell a UE (user equipment) if the target eNB usesdelta or full configuration method, and means a signaling of a certainRRC Release version from the source eNB to the target eNB duringhandover preparation for enabling the target eNB to decide which methodis or should be used. Delta signaling may be supported if the target eNBRRC protocol version is equal or newer than the one which the source eNBis using.

To use the full signaling, it is proposed to include e.g. one bit forindicating e.g. in the RRC connection reconfiguration message in Rel-8or onward. Thus, in case the “full signaling Indicator” is set to “yes”,the UE may clearly know that the RRC connection reconfiguration messageis not based on the delta signaling. As this full signaling may berequired when the source eNB's RRC protocol release is higher than thetarget eNB's RRC protocol release, having “full signaling indicator” inRel-8 onward may solve the problem.

To decide whether the “full signaling indicator” should be set to “yes”or not, the target eNB may make a decision e.g. during HO preparation,because this information element may be included e.g. in the RRCconnection reconfiguration message and may be sent to the source eNBe.g. in the Handover Request Acknowledge message.

In other words, it is proposed that the source eNB may indicate therelease of RRC protocol of the source eNB to the target eNB during thehandover preparation. This can be included in the RRC container or canbe signaled over X2 and/or over S1 in the X2 and/or S1 applicationprotocol. After the target eNB learns the release of RRC protocol whichthe source eNB is using, and if the release is higher than the one thetarget eNB is using or the target eNB does not understand the release(e.g. because the source eNB RRC protocol release indicator is higherthan what the target eNB is supporting), the target eNB may use the fallsignaling. If the source eNB RRC protocol release is lower or equal thanthe target eNB RRC protocol release, the target eNB can use theso-called delta signaling.

In other words, the signaling of the first protocol version may beperformed e.g. by an RRC container or a X1/S1 message. The signalingitself may not relate to delta or full signaling. The source eNB mayindicate e.g. its RRC protocol release via the RRC container (e.g.handover preparation information message) or the X1/S1 message.(Handover Request message/Handover Required message) And gradually, theRRC container may be encapsulated in the X1/S2 message. Thus, theHandover Command may be a RRC message and the Handover RequestAcknowledgement message may be X2 message. The handover command may beencapsulated in the Handover Request acknowledge message, and the sourceeNB may transmit the handover command to the UE, because the handovercommand message may be the form which the UE can process. Finally,full/delta signaling may be related to that handover command message,which constructed in the target eNB and is sent to the UE via the sourceeNB. Accordingly, a one bit indicator in the same message (i.e. handovercommand message) may be used so that the UE can configure parametersproperly.

Further Examples

For the purpose of the present invention as described herein above, itshould be noted that

-   -   a circuitry may refer to at least one of, or hybrids of the        following:    -   (a) to pure hardware circuit implementations (such as        implementations purely in analog and/or digital circuitry), and    -   (b) to combinations of circuits and software (and/or firmware),        such as (as applicable):        -   (i) a combination of processor(s), or        -   (ii) portions of processor(s)/software (including digital            signal processor(s)), software and memory (or memories) that            work together to cause an apparatus as defined hereinabove            to perform various functions, and    -   (c) to circuits, such as (micro)processor(s) or a portion of (a)        (micro)processor(s) that require software and/or firmware for        operation even if the software or firmware is not physically        present;    -   a processor may be any processing unit, such as CPU, arithmetic        and logic unit (ALU), microprocessor unit (MPU), digital signal        processor (DSP) etc., be it a single core processor, dual core        processor or multi-core processor;    -   a program may be embodied by or on any computer program        (product), computer readable medium, processor(s), memory (or        memories), circuitry, circuits, random access memory (RAM),        read-only memory (ROM) and/or data structure(s), be it e.g. as        compiled/non-compiled program (source) code, executable object,        (meta)file or the like;    -   an access technology may be any technology by means of which a        user equipment can access an access network (or base station,        respectively). Any present or future technology, such as WiMAX        (Worldwide Interoperability for Microwave Access) or WLAN        (Wireless Local area Network), BlueTooth, Infrared, and the like        may be used; although the above technologies are mostly wireless        access technologies, e.g. in different radio spectra, access        technology in the sense of the present invention may also imply        wirebound technologies, e.g. IP based access technologies like        cable networks or fixed line.    -   a network may be any device, unit or means by which a station        entity or other user equipment may connect to and/or utilize        services offered by the access network; such services include,        among others, data and/or (audio-) visual communication, data        download etc.;    -   generally, the present invention may be applicable in those        network/user equipment environments relying on a data packet        based transmission scheme according to which data are        transmitted in data packets and which are, for example, based on        the internet protocol (IP). The present invention is, however,        not limited thereto, and any other present or future IP or        mobile IP (MIP) version, or, more generally, a protocol        following similar principles as (M)IPv4/6, is also applicable;    -   a user equipment may be any device, unit or means by which a        system user may experience services from an access network;    -   method steps likely to be implemented as software code portions        and being run using a processor at a network element or terminal        (as examples of devices, apparatuses and/or modules thereof, or        as examples of entities including apparatuses, circuitries        and/or modules therefore), are software code independent and can        be specified using any known or future developed programming        language as long as the functionality defined by the method        steps is preserved;    -   generally, any method step is suitable to be implemented as        software or by hardware without changing the idea of the        invention in terms of the functionality implemented;    -   method steps and/or devices, units or means likely to be        implemented as hardware components at the above-defined        apparatuses, or any module(s)/circuitry(ies) thereof, are        hardware independent and can be implemented using any known or        future developed hardware technology or any hybrids of these,        such as MOS (Metal Oxide Semiconductor), CMOS (Complementary        MOS), BiMOS (Bipolar MOS), BiCMOS (Bipolar CMOS), ECL (Emitter        Coupled Logic), TTL (Transistor-Transistor Logic), etc., using        for example ASIC (Application Specific IC (Integrated Circuit))        components, FPGA (Field-programmable Gate Arrays) components,        CPLD (Complex Programmable Logic Device) components or DSP        (Digital Signal Processor) components; in addition, any method        steps and/or devices, units or means likely to be implemented as        software components may alternatively be based on any security        architecture capable e.g. of authentication, authorization,        keying and/or traffic protection;    -   devices, units, circuitries or means (e.g. the above-defined        apparatuses, or any one of their respective means) can be        implemented as individual devices, units or means, but this does        not exclude that they are implemented in a distributed fashion        throughout the system, as long as the functionality of the        device, unit. circuitry or means is preserved;    -   an apparatus may be represented by a semiconductor chip, a        chipset, a (hardware) module comprising such chip or chipset, or        a circuitry; this, however, does not exclude the possibility        that a functionality of an apparatus, module or circuitry,        instead of being hardware implemented, be implemented as        software in a (software) module such as a computer program or a        computer program product comprising executable software code        portions for execution/being run on a processor;    -   a device may be regarded as an apparatus or as an assembly of        more than one apparatus, whether functionally in cooperation        with each other or functionally independently of each other but        in a same device housing, for example.

According to an example of the present invention, in a first aspect,this object is for example achieved by a method comprising:

-   -   receiving, in a handover request message, an indication of a        first protocol version;    -   deciding, based on the received indication of the first protocol        version and a second protocol version, on a value of an        information element comprised in a handover request        acknowledgement message to be transmitted, the information        element indicating usage of one of a first signaling scheme and        a second signaling scheme different from the first signaling        scheme; and    -   transmitting the handover request acknowledgement message        comprising the information element indicating usage of the one        of the first and second signaling scheme.

According to further refinements of the example of the present inventionas defined under the above first aspect,

-   -   the deciding is performed during a handover preparation.

According to an example of the present invention, in a second aspect,this object is for example achieved by a method comprising:

-   -   transmitting, in a handover request message, an indication of a        first protocol version; and    -   receiving, responsive to the transmitting, a handover request        acknowledgement message comprising an information element        indicating usage of one of a first signaling scheme and a second        signaling scheme different from the first signaling scheme, the        usage of the one of the first and second signaling schemes        having been decided based on the first protocol version and an        external second protocol version.

According to further refinements of the example of the present inventionas defined under the above second aspect,

-   -   the method further comprises extracting an handover command        message from the received handover request acknowledgement        message, the handover command message comprising the information        element;    -   the method further comprises transmitting, after the receiving,        the handover command message to a user equipment.

According to further refinements of the example of the present inventionas defined under the above first and second aspects,

-   -   the indication of the first protocol version is comprised in a        radio resource control container;    -   the indication of the first protocol version is signaled in an        X2/S1 application signaling protocol.

According to an example of the present invention, in a third aspect,this object is for example achieved by a method comprising:

-   -   receiving a handover command message comprising an information        element indicating usage of one of a first signaling scheme and        a second signaling scheme different from the first signaling        scheme, the usage of the one of the first and second signaling        schemes having been decided based on an external first protocol        version and an external second protocol version; and    -   configuring according to one of the first and second signaling        schemes indicated by the information element.

According to further refinements of the example of the present inventionas defined under the above first to third aspects,

-   -   the first signaling scheme utilizes handover command messages of        full configuration;    -   the information element is set to affirmative;        -   the first protocol version is higher than the second            protocol version;        -   the second signaling scheme utilizes handover command            messages of reduced configuration;        -   the information element is set to non-affirmative;        -   the first protocol version is equal to or lower than the            second protocol version;        -   the protocol version is constituted by a protocol release;        -   the information element is constituted by at least one bit;        -   the handover request acknowledgement message is constituted            by or encapsulates a radio resource control connection            reconfiguration message;        -   the first protocol is constituted by a radio resource            control protocol of a handover source entity;        -   the indication of the first protocol version is an            enumerated information element;        -   the second protocol is constituted by a radio resource            control protocol of a handover target entity;        -   the handover command messages of full configuration are            constituted by radio resource control connection            reconfiguration messages;        -   the handover command messages of delta configuration are            constituted by radio resource control connection            reconfiguration messages;        -   the radio resource control container is constituted by an            handover preparation information message.

According to an example of the present invention, in a fourth aspect,this object is for example achieved by an apparatus comprising:

-   -   means for receiving, in a handover request message, an        indication of a first protocol version;    -   means for deciding, based on the received indication of the        first protocol version and a second protocol version, on a value        of an information element comprised in a handover request        acknowledgement message to be transmitted, the information        element indicating usage of one of a first signaling scheme and        a second signaling scheme different from the first signaling        scheme; and    -   means for transmitting the handover request acknowledgement        message comprising the information element indicating usage of        the one of the first and second signaling schemes.

According to further refinements of the example of the present inventionas defined under the above fourth aspect,

-   -   the means for deciding is configured to perform during a        handover preparation.

According to an example of the present invention, in a fifth aspect,this object is for example achieved by an apparatus comprising:

-   -   means for transmitting, in a handover request message, an        indication of a first protocol version; and    -   means for receiving, responsive to the means for transmitting, a        handover request acknowledgement message comprising an        information element indicating usage of one of a first signaling        scheme and a second signaling scheme different from the first        signaling scheme, the usage of the one of the first and second        signaling schemes having been decided based on the first        protocol version and an external second protocol version.

According to further refinements of the example of the present inventionas defined under the above fifth aspect,

-   -   the apparatus further comprises means for extracting an handover        command message from the received handover request        acknowledgement message, the handover command message comprising        the information element;    -   the apparatus further comprises means for transmitting, after        the receiving, the handover command message to a user equipment.

According to further refinements of the example of the present inventionas defined under the above fourth and fifth aspects,

-   -   the indication of the first protocol version is comprised in a        radio resource control container;    -   the indication of the first protocol version is configured to be        signaled in an X2/S1 application signaling protocol.

According to an example of the present invention, in a sixth aspect,this object is for example achieved by an apparatus comprising:

-   -   means for receiving a handover command message comprising an        information element indicating usage of one of a first signaling        scheme and a second signaling scheme different from the first        signaling scheme, the usage of the one of the first and second        signaling schemes having been decided based on an external first        protocol version and an external second protocol version; and    -   means for configuring according to one of the first and second        signaling schemes indicated by the information element.

According to further refinements of the example of the present inventionas defined under the above fourth to sixth aspects,

-   -   the first signaling scheme is configured to utilize handover        command messages of full configuration;    -   the information element is configured to be set to affirmative;    -   the first protocol version is higher than the second protocol        version;    -   the second signaling scheme is configured to utilize handover        command messages of reduced configuration;    -   the information element is configured to be set to        non-affirmative;    -   the first protocol version is equal to or lower than the second        protocol version;    -   the protocol version is constituted by a protocol release; —the        information element is constituted by at least one bit;    -   the handover request acknowledgement message is constituted by        or encapsulates a radio resource control connection        reconfiguration message;    -   the first protocol is constituted by a radio resource control        protocol of a handover source entity;    -   the indication of the first protocol version is an enumerated        information element;    -   the second protocol is constituted by a radio resource control        protocol of a handover target entity;    -   the handover command messages of full configuration are        constituted by radio resource control connection reconfiguration        messages;    -   the handover command messages of delta configuration are        constituted by radio resource control connection reconfiguration        messages;    -   the radio resource control container is constituted by a        handover preparation information message;    -   at least one, or more of means for receiving, means for        deciding, means for transmitting, means for extracting, means        for configuring and the apparatus is implemented as a chipset,        module or subassembly.

According to an example of the present invention, in a seventh aspect,this object is for example achieved by an apparatus comprising:

-   -   a receiver configured to receive, in a handover request message,        an indication of a first protocol version;    -   a decider configured to decided, based on the received        indication of the first protocol version and a second protocol        version, on a value of an information element comprised in a        handover request acknowledgement message to be transmitted, the        information element indicating usage of one of a first signaling        scheme and a second signaling scheme different from the first        signaling scheme; and    -   a transmitter configured to transmit the handover request        acknowledgement message comprising the information element        indicating usage of the one of the first and second signaling        schemes.

According to further refinements of the example of the present inventionas defined under the above seventh aspect,

-   -   the decider is configured to perform during a handover        preparation.

According to an example of the present invention, in an eighth aspect,this object is for example achieved by an apparatus comprising:

-   -   a transmitter configured to transmit, in a handover request        message, an indication of a first protocol version; and    -   a receiver configured to receive, responsive to the transmitter,        a handover request acknowledgement message comprising an        information element indicating usage of one of a first signaling        scheme and a second signaling scheme different from the first        signaling scheme, the usage of the one of the first and second        signaling schemes having been decided based on the first        protocol version and an external second protocol version.

According to further refinements of the example of the present inventionas defined under the above eighth aspect,

-   -   the apparatus further comprises an extractor configured to        extract an handover command message from the received handover        request acknowledgement message, the handover command message        comprising the information element;    -   the apparatus further comprises a transmitter configured to        transmit, after the receiving, the handover command message to a        user equipment.

According to further refinements of the example of the present inventionas defined under the above seventh and eighth aspects,

-   -   the indication of the first protocol version is comprised in a        radio resource control container;    -   the indication of the first protocol version is configured to be        signaled in an X2/S1 application signaling protocol.

According to an example of the present invention, in a ninth aspect,this object is for example achieved by an apparatus comprising:

-   -   a receiver configured to receive a handover command message        comprising an information element indicating usage of one of a        first signaling scheme and a second signaling scheme different        from the first signaling scheme, the usage of the one of the        first and second signaling schemes having been decided based on        an external first protocol version and an external second        protocol version; and    -   a configurator configured to configure according to one of the        first and second signaling schemes indicated by the information        element.

According to further refinements of the example of the present inventionas defined under the above seventh to ninth aspects,

-   -   the first signaling scheme is configured to utilize handover        command messages of full configuration;    -   the information element is configured to be set to affirmative;    -   the first protocol version is higher than the second protocol        version;    -   the second signaling scheme is configured to utilize handover        command messages of reduced configuration;    -   the information element is configured to be set to        non-affirmative;    -   the first protocol version is equal to or lower than the second        protocol version;    -   the protocol version is constituted by a protocol release;    -   the information element is constituted by at least one bit;    -   the handover request acknowledgement message is constituted by        or encapsulates a radio resource control connection        reconfiguration message;    -   the first protocol is constituted by a radio resource control        protocol of a handover source entity;    -   the indication of the first protocol version is an enumerated        information element;    -   the second protocol is constituted by a radio resource control        protocol of a handover target entity;    -   the handover command messages of full configuration are        constituted by radio resource control connection reconfiguration        messages;    -   the handover command messages of delta configuration are        constituted by radio resource control connection reconfiguration        messages;    -   the radio resource control container is constituted by a        handover preparation information message;    -   at least one, or more of the receiver, the decider, the        extractor, the configurator and the apparatus is implemented as        a chipset, module or subassembly.

According to an example of the present invention, in a tenth aspect,this object is for example achieved by a system comprising:

-   -   an apparatus according to the above fourth or seventh aspects;    -   an apparatus according to the above fifth or eighth aspects; and    -   an apparatus according to the above sixth or ninth aspects.

According to an example of the present invention, in an eleventh aspect,this object is for example achieved by a computer program productcomprising code means for performing a method according to any one ofthe above first to third aspects when run on a processing means ormodule.

According to an example of the present invention, in a twelfth aspect,this object is for example achieved by a computer program comprisingcode means for performing, when run on a processing means or module, amethod comprising:

-   -   receiving, in a handover request message, an indication of a        first protocol version;    -   deciding, based on the received indication of the first protocol        version and a second protocol version, on a value of an        information element comprised in a handover request        acknowledgement message to be transmitted, the information        element indicating usage of one of a first signaling scheme and        a second signaling scheme different from the first signaling        scheme; and    -   transmitting the handover request acknowledgement message        comprising the information element indicating usage of the one        of the first and second signaling scheme.

According to an example of the present invention, in a thirteenthaspect, this object is for example achieved by a computer programcomprising code means for performing, when run on a processing means ormodule, a method comprising:

-   -   transmitting, in a handover request message, an indication of a        first protocol version; and    -   receiving, responsive to the transmitting, a handover request        acknowledgement message comprising an information element        indicating usage of one of a first signaling scheme and a second        signaling scheme different from the first signaling scheme, the        usage of the one of the first and second signaling schemes        having been decided based on the first protocol version and an        external second protocol version.

According to an example of the present invention, in a fourteenthaspect, this object is for example achieved by a computer programcomprising code means for performing, when run on a processing means ormodule, a method comprising:

-   -   receiving a handover command message comprising an information        element indicating usage of one of a first signaling scheme and        a second signaling scheme different from the first signaling        scheme, the usage of the one of the first and second signaling        schemes having been decided based on an external first protocol        version and an external second protocol version; and    -   configuring according to one of the first and second signaling        schemes indicated by the information element.

According to an example of the present invention, in a fifteenth aspect,this object is for example achieved by a data structure comprising:

-   -   an information element comprising an information element        indicating usage of one of a first signaling scheme and a second        signaling scheme different from the first signaling scheme, the        usage of the one of the first and second signaling schemes        having been decided based on the first protocol version and an        external second protocol version.

According to further refinements of the example of the present inventionas defined under the above fifteenth aspect,

-   -   the protocol version is constituted by a protocol release;    -   the information element is constituted by at least one bit;    -   the data structure is constituted by a handover request        acknowledgement message;    -   the handover request acknowledgement message is constituted by        or encapsulates a radio resource control connection        reconfiguration message;    -   the first protocol is constituted by a radio resource control        protocol of a handover source entity;    -   the indication of the first protocol version is an enumerated        information element;    -   the second protocol is constituted by a radio resource control        protocol of a handover target entity;    -   the handover command messages of full configuration are        constituted by radio resource control connection reconfiguration        messages;    -   the handover command messages of delta configuration are        constituted by radio resource control connection reconfiguration        messages;    -   the radio resource control container is constituted by a        handover preparation information message.

Although the present invention has been described herein before withreference to particular embodiments thereof, the present invention isnot limited thereto and various modification can be made thereto.

What is claimed is:
 1. A target base station (BS), supporting up to andincluding a protocol release M, capable of supporting a user equipment(UE) handover from a source BS supporting up to and including a protocolrelease N, the target BS comprising: a transceiver configured to receivea handover request message from the source BS, the handover requestmessage indicating a first protocol release used by the source BS toconfigure the UE; and the transceiver further configured to transmit ahandover request acknowledge message to the source BS, wherein, on acondition that the first protocol release is newer than the protocolrelease M, the handover request acknowledge message comprising a one bitindication that the UE perform a full configuration.
 2. The target BS ofclaim 1, wherein the first protocol release is later than the protocolrelease M, and is a protocol release up to and including the protocolrelease N.
 3. The target BS of claim 1, wherein the first protocolrelease is a first radio resource control (RRC) protocol release and theprotocol release M is a second RRC protocol release.
 4. The target BS ofclaim 1, wherein the handover request message includes an enumeratedinformation element indicating the first protocol release.
 5. The targetBS of claim 1, wherein the full configuration enables the UE to becompatible with one or more protocol releases supported by the targetBS.
 6. A non-transitory computer readable storage medium comprisingexecutable code stored thereon for supporting up to and including aprotocol release M and for supporting a user equipment (UE) handover toan apparatus from a source BS supporting up to and including a protocolrelease N, wherein the executable code, when executed by a processor,causes the apparatus to at least: receive a handover request messagefrom the source BS, the handover request message indicating a firstprotocol release used by the source BS to configure the UE; and transmita handover request acknowledge message to the source BS, wherein, on acondition that the first protocol release is newer than the protocolrelease M, the handover request acknowledge message comprising a one bitindication that the UE perform a full configuration.
 7. Thenon-transitory computer readable storage medium of claim 6, wherein thefirst protocol release is later than the protocol release M, and is aprotocol release up to and including the protocol release N.
 8. Thenon-transitory computer readable storage medium of claim 6, wherein thefirst protocol release is a first radio resource control (RRC) protocolrelease and the protocol release M is a second RRC protocol release. 9.The non-transitory computer readable storage medium of claim 6, whereinthe handover request message includes an enumerated information elementindicating the first protocol release.
 10. The non-transitory computerreadable storage medium of claim 6, wherein the full configurationenables the UE to be compatible with one or more protocol releasessupported by the apparatus.
 11. A method performed by a target basestation (BS), the target BS supporting up to and including a protocolrelease M and the target BS being capable of supporting a user equipment(UE) handover from a source BS supporting up to and including a protocolrelease N, the method comprising: receiving a handover request messagefrom the source BS, the handover request message indicating a firstprotocol release used by the source BS to configure the UE; andtransmitting a handover request acknowledge message to the source BS,wherein, on a condition that the first protocol release is newer thanthe protocol release M, the handover request acknowledge messagecomprising a one bit indication that the UE perform a fullconfiguration.
 12. The method of claim 11, wherein the first protocolrelease is later than the protocol release M, and is a protocol releaseup to and including the protocol release N.
 13. The method of claim 11,wherein the first protocol release is a first radio resource control(RRC) protocol release and the protocol release M is a second RRCprotocol release.
 14. The method of claim 11, wherein the handoverrequest message includes an enumerated information element indicatingthe first protocol release.
 15. The method of claim 11, wherein the fullconfiguration enables the UE to be compatible with one or more protocolreleases supported by the target BS.
 16. A source base station (BS),supporting up to and including a protocol release N, capable ofsupporting a user equipment (UE) handover from the source BS to a targetBS, supporting up to and including a protocol release M, the source BScomprising: a first transceiver configured to: transmit a handoverrequest message to the target BS, the handover request messageindicating a first protocol release used by the source BS to configurethe UE; and receive a handover request acknowledge message from thetarget BS, wherein, on a condition that the first protocol release isnewer than the protocol release M, the handover request acknowledgemessage comprising a one bit indication that the UE perform a fullconfiguration.
 17. The source BS of claim 16, wherein the handoverrequest acknowledge message includes a handover command message.
 18. Thesource BS of claim 17, further comprising: a second transceiverconfigured to transmit the handover command message to the UE.
 19. Thesource BS of claim 16, wherein the first protocol release is later thanthe protocol release M, and is a protocol release up to and includingthe protocol release N.
 20. The source BS of claim 16, wherein the firstprotocol release is a first radio resource control (RRC) protocolrelease and the protocol release M is a second RRC protocol release. 21.The source BS of claim 16, wherein the handover request message includesan enumerated information element indicating the first protocol release.22. A non-transitory computer readable storage medium comprisingexecutable code stored thereon for supporting up to and including aprotocol release N, capable of supporting a user equipment (UE) handoverfrom an apparatus to a target BS, supporting up to and including aprotocol release M, wherein the executable code, when executed by aprocessor, causes the apparatus to at least: transmit a handover requestmessage to the target BS, the handover request message indicating afirst protocol release used by the apparatus to configure the UE; andreceive a handover request acknowledge message from the target BS,wherein, on a condition that the first protocol release is newer thanthe protocol release M, the handover request acknowledge messagecomprising a one bit indication that the UE perform a fullconfiguration.
 23. The non-transitory computer readable storage mediumof claim 22, wherein the handover request acknowledge message includes ahandover command message.
 24. The non-transitory computer readablestorage medium of claim 23, wherein the executable code, when executedby the processor, further causes the apparatus to: transmit the handovercommand message to the UE.
 25. The non-transitory computer readablestorage medium of claim 22, wherein the first protocol release is laterthan the protocol release M, and is a protocol release up to andincluding the protocol release N.
 26. The non-transitory computerreadable storage medium of claim 22, wherein the first protocol releaseis a first radio resource control (RRC) protocol release and theprotocol release M is a second RRC protocol release.
 27. Thenon-transitory computer readable storage medium of claim 22, wherein thehandover request message includes an enumerated information elementindicating the first protocol release.
 28. A method performed by asource base station (BS), the source BS supporting up to and including aprotocol release N and the source BS being capable of supporting a userequipment (UE) handover from the source BS to a target BS, supporting upto and including a protocol release M, the method comprising:transmitting a handover request message to the target BS, the handoverrequest message indicating a first protocol release used by the sourceBS to configure the UE; and receiving a handover request acknowledgemessage from the target BS, wherein, on a condition that the firstprotocol release is newer than the protocol release M, the handoverrequest acknowledge message comprising a one bit indication that the UEperform a full configuration.
 29. The method of claim 28, wherein thehandover request acknowledge message includes a handover commandmessage.
 30. The method of claim 29, further comprising: transmittingthe handover command message to the UE.
 31. The method of claim 28,wherein the first protocol release is later than the protocol release M,and is a protocol release up to and including the protocol release N.32. The method of claim 28, wherein the first protocol release is afirst radio resource control (RRC) protocol release and the protocolrelease M is a second RRC protocol release.
 33. The method of claim 28,wherein the handover request message includes an enumerated informationelement indicating the first protocol release.